The present invention relates to the hydraulic actuated apparatus including a hydraulically actuated reciprocating element and particularly to a hydraulic pressure booster having a unique associated control valve means to control the developing of the mechanical motion and the development of high hydraulic pressures where required.
Hydraulic operating and control systems are widely employed in industry. Although they have many advantages, the development of relatively high working pressures from a low pressure input generally require special apparatus which are generally identified as a booster or intensifier. Various such pressure boosters or intensifiers have been suggested wherein in a relatively large quantity of low pressure fluid acts over a relatively large area piston and developes a mechanical force upon a piston of small area which produces a relatively high pressure output. The pressure multiplication is in direct ratio to the piston areas. The prior art hydraulic boosters have employed various controls to create the desired high pressure output, including different electrical, mechanical and hydraulic control systems. A simple hydraulically actuated control is, of course highly desirable. Such control should be adapted to conventional and inexpensive manufacturing and operate directly from the low pressure source to avoid the necessity for separate mechanical and electrical actuating devices. Racine Hydraulics and Machinery of Racine, Wisconsin, U.S.A., for example, uses a hydraulically shifted booster in which a spool valve is connected to a suitable lever which in turn activates a pilot valve to shift a separate four way valve coupling in which the relatively low pressure oil acts over a relatively large piston and moves a relatively small piston and thereby forces oil out under high pressure. The pressure increase is directly proportional and the volume inversely proportional to the differences of the piston areas. The control may be and is generally connected by external flow lines to a pressure sensitive valve unit to permit normal low pressure operation of the load until such time as the load builds to a higher pressure and then automatically shifts to the booster output.
Although pressure booster devices are available and have been relatively widely employed in the industry, there is a need for reliable, in-line intensifying apparatus which can be constructed with commercial production techniques and at low cost. Further, an intensifier unit having integrated hydraulic components and internal passageways to eliminate the usual external flow lines, fittings and the like would avoid serious practical problems in usage and permit an especially desirable construction.